Hi, Need some advice please. I have a D700 and SB900 and SB600 speedlites and I am experimenting with the wireless flash system which I note only works when my commander unit ( The built in flash ) can see the speedlites with its infra red beam.

Now suppose I want to place a flash behind a model to rim light , hair light or light a backdrop with a gel . I need the model to be in front of the flash which has been positioned on a low lighting stand

Is there a way round this I have not thought of or have I got to start investing in expensive radio triggers like pocket wizards?